Communication cable

Abstract

A communication cable that includes a twisted wire pair that includes a pair of insulated wires that are twisted together and that each include a conductor and an insulating covering that covers an outer periphery of the conductor; and a sheath that is made of an insulating material and continuously covers an entire outer periphery of the twisted wire pair about a center along a longitudinal axis of the twisted wire pair, wherein the sheath has a dielectric loss tangent of 0.0001 or more in a frequency range of 1 to 50 MHz.

The invention claimed is: 
     
       1. A communication cable comprising:
 a twisted wire pair that includes a pair of insulated wires that are twisted together and that each include a conductor and an insulating covering that covers an outer periphery of the conductor; and 
 a sheath that is made of an insulating material and continuously covers an entire outer periphery of the twisted wire pair about a center along a longitudinal axis of the twisted wire pair, wherein 
 the twisted wire pair covered by the sheath is only one twisted wire pair, and the sheath continuously covers the entire outer periphery of the only one twisted wire pair, 
 the insulating covering includes only one layer, the one layer having a smaller dielectric loss tangent than the sheath has in a frequency range of 1 to 50 MHz, and 
 the sheath has a dielectric loss tangent of 0.0001 or more in the frequency range of 1 to 50 MHz, 
 the conductor has a breaking elongation of 7% or more and a twist pitch of the twisted wire pair is 15 times or more of an outer diameter of each of the insulated wires, or 
 the conductor has a breaking elongation of less than 7% and a twist pitch of the twisted wire pair is 25 times or leas of the outer diameter of each of the insulated wires. 
 
     
     
       2. The communication cable according to  claim 1 ,
 wherein the dielectric loss tangent of the sheath is 0.08 or less in the frequency range of 1 to 50 MHz. 
 
     
     
       3. The communication cable according to  claim 1 ,
 wherein the sheath includes an outer layer and an inner layer that is disposed inside the outer layer, and a dielectric loss tangent of the outer layer is larger than a dielectric loss tangent of the inner layer. 
 
     
     
       4. The communication cable according to  claim 1 ,
 wherein the insulating covering has a dielectric loss tangent of 0.001 or less in the frequency range of 1 to 50 MHz. 
 
     
     
       5. The communication cable according to  claim 1 ,
 wherein the insulating covering has a dielectric loss tangent of 0.0006 or less in the frequency range of 1 to 50 MHz.